1. Field of the Invention
The present invention relates to a die-punch machine, more precisely relates to a die-punch machine for press-machining works, e.g., metal plates, which comprises: a punch; a first member for holding the punch; a second member being capable of relatively moving to and away from the first member; and a die being held by the second member, wherein a front end section of the punch is capable of being inserted into the die.
2. Description of Background Art
Conventionally, for example, radiating fins of heat exchangers, which are used in room or car air conditioners, are manufactured by press-machining processes. One of the processes is disclosed in U.S. Pat. No. 5,237,849. The process shown in the U.S. patent will be explained with reference to FIGS. 9A-9F.
Firstly, a cone section 2 is formed in a metal plate 1 (FIG. 9A). A flat section 4 is formed by extending a thin top portion of the conical section 2, then a truncated cone section 3 (FIG. 9B). A hole 6 is bored in the flat section 4 of the truncated cone section 3, and the hole 6 is bored so as to form a projected section 7 on an edge of the hole 6 (FIG. 9C). Then the projected section 7 is ironed to form a collar 8 (and 9) having prescribed height (FIGS. 9D and 9E). Finally, a top edge of the collar 8 is bent outward to form a flange section 10 (FIG. 9F).
The above described press-machining steps 9A-9F can be executed by a conventional die-punch machine shown in FIG. 10. In the die-punch machine, a metal plate 1, which has been fed in a direction of an arrow A, is intermittently moved. While being intermittently, the metal plate 1 is passed through machining stages 102, 104, 106, 108 and 110, each of which has an upper member held by an upper base board 100 and a lower member held by a lower base board 200, in order, and finally discharged in a direction of an arrow B.
The step shown in FIG. 9A is executed in the stage 102; the step shown in FIG. 9B is executed in the stage 104; the step shown in FIG. 9C is executed in the stage 106; the steps shown in FIGS. 9D and 9E are executed in the stage 108; and the step shown in FIG. 9F is executed in the stage 110.
Each stage has a proper punch and a proper die for the machining step assigned thereto. A partial sectional view of the stage 108 for the steps shown in FIGS. 9D and 9E is shown in FIG. 11.
The stage 108 has an upper member 300 and a lower member 400. In the upper member 300, a die 116 is held by plates 112 and 114.
A lower end of the die 116 is slightly projected downward from a bottom face of the plate 114 of the upper member 300. A knock-out 118, which is an example of an ejecting member, is inserted in the die 116. The knock-out 118 is always biased toward the lower member 400 by a spring 120. Upon completing the ironing step by inserting a punch 128 in the die 116, the knock-out 118 is moved downward together with the punch 128. By the downward movement of the knock-out 118, the collar 8 (and 9), which has been stuck on an inner face of the die 116, is ejected from the die 116.
A columnar member 132 is inserted in a cylindrical member 126, which is fixed by plates 122 and 124 of the lower member 400. By inserting the columnar member 132, an upper end of the punch 128 is fixed and projects from the cylindrical member 126.
The diameter of the upper end section 138 of the punch 128 is smaller than the diameter of a mid-section thereof. There is formed a tapered section 136 immediately below the upper end section 138.
A stripper plate 130 is provided in the lower member 400. The stripper plate 130 is always biased toward the upper member 300 by a biasing member 131, so that there is formed a clearance between the stripper plate 130 and the plate 122. A through-hole 134 is bored therein through which the upper end section of the punch 128 can be passed in a stripper plate 130. The height of the stripper plate 130 is adjusted so as to not project from the upper end of the punch 128 from an upper face of the stripper plate 130 when no downward force works on the stripper plate 130. The metal plate 1 having the projected section 7 (see FIG. 9C) is mounted on the upper face of the stripper plate 130, and the ironing steps shown in FIGS. 9D and 9E are executed.
When the ironing steps are executed, the upper member 300 is moved downward, so that the lower end face of the die 116 pushes the stripper plate 130 downward. By the downward movement of the stripper plate 130, the distance between the stripper plate 130 and the plate 122 is shortened. Then the upper end section of the punch 128 goes into the through-hole 134 and projects from the upper face of the stripper plate 130. When the upper member 300 is further moved downward, the upper end section of the punch 128 goes into the die 116 and pushes the knock-out 118 upward against the elasticity of the spring 120. With the movement of the die 116, the projected section 7 is ironed by the punch 128 and the inner face of the die 116. The ironing is completed when the tapered section 136 of the punch 128 passes through the projected section 7 (see FIG. 12).
Upon completing the ironing, the upper member 300 is moved upward, and the upper end section of the punch 128 comes off from the die 116. With the movement, the knock-out 118, which is contacted the punch 128 by the elasticity of the spring 120, is moved downward, so that the collars 8 (9) stuck on the inner face of the die 116 is ejected downward.
The conventional die-punch machine shown in FIG. 10 has the stages 102, 104, 106 and 110, each of which has a proper die and a proper punch, besides the stage 108 shown in FIG. 11. By feeding the metal plate 1 in the direction of the arrows A and B, the collared through-holes can be formed in the metal plate 1.
In the conventional die-punch machine shown in FIG. 10, machining oil is supplied to the metal plate 1 so as to raise the efficiency of the press machining. Volatile oils are preferably used as machining oils but they volatilize in a short time. Thus, even if they are supplied before the metal plate 1 is fed, almost volatile oil will volatilize before the metal plate 1 is passed all stages. So practically the efficiency of the press machining cannot be raised.
To overcome the disadvantage, the inventors invented an improved die-punch machine, which has been disclosed in U.S. Pat. No. 5,159,826. The improved machine will be explained with reference to FIG. 13.
In a machine shown in FIG. 13, oil paths 138 and 140 are formed in the punch 128, the columnar member 132 and the knock-out 118. By forming the oil paths 138 and 140, the machine oil can be supplied to the punch 128 and the metal plate 1. In each machining stage, the machining oil, which has been formed into a mist, is sprayed to the metal plate 1 on the stripper plate 130 when the press machining is executed. By spraying the oil mist, the metal plate 1, which is fully supplied with oil, is machined in each stage.
However, in the die-punch machine shown in FIG. 13, openings of the oil paths 138 and 140 are closed when the upper end face of the punch 128 contacts the lower end face of the knock-out 118, so that the oil mist cannot be sprayed. Namely, the machining oil cannot be supplied to the projecting section 7 to be machined while the ironing is executed.
The machining oil introduced through the oil paths 138 and 140 can be directly sprayed to the tapered section 136 of the punch 128 for ironing until the upper end face of the punch 128 contacts the lower end face of the knock-out 118. But the machining oil cannot be sprayed to the tapered section 136 after the upper end face of the punch 128 contacts the lower end face of the knock-out 118.
As described above, in the conventional die-punch machine, machining oils cannot be directly supplied to not only workpieces, e.g., the metal plate, to be machined but also front end sections of punches while the ironing work is executed. Thus, a large amount of machining oils must be supplied prior to the ironing work, and oil consumption must be increased.